FIGS. 11 and 12 show an example of conventional image reader. FIG. 12 is a sectional view taken along lines XII-XII in FIG. 11. The conventional image reader X reads the content of a document Dc as image data. The document Dc is transferred in the secondary scanning direction, which is the right and left direction in FIG. 12, by e.g. a platen roller Pr. The image reader X includes a case 91, a substrate 92, a light source device 93, a light guide member 94, sensor IC chips 95, a lens array 96, a transparent plate 97 and a pair of reflectors 98A, 98B.
The case 91 is narrow and elongated in the primary scanning direction which is the right and left direction in FIG. 11 (i.e., perpendicular to the secondary scanning direction). The substrate 92 has an elongated rectangular shape extending in the primary scanning direction and is fitted in the case 91. The light source device 93 emits light for reading an image. The light source device 93 is mounted on the substrate 92.
The light guide member 94 is made of a transparent resin and directs the light emitted from the light source device 93 toward the document Dc. The light guide member 94 is narrow and elongated in the primary scanning direction. The light guide member 94 includes a light incident surface 94a, a reflecting surface 94b and a light emitting surface 94c. 
The light incident surface 94a faces the light source device 93. The light emitted from the light source device 93 enters the light guide member 94 through the light incident surface 94a. The reflecting surface 94b is inclined with respect to the primary scanning direction. The light traveling from the light incident surface 94a is reflected by the reflecting surface 94b in the primary scanning direction. The light emitting surface 94c is narrow and elongated in the primary scanning direction. The light traveling through the light guide member 94 is emitted from the light emitting surface 94c toward the document Dc as linear light extending in the primary scanning direction.
The paired reflectors 98A and 98B may be made of a white resin, for example. The reflectors 98A and 98B prevent light from leaking from the light guide member 94.
The light emitted from the light guide member 94 passes through the transparent plate 97 to impinge on the document Dc and is reflected by the document Dc. The reflected light is converged onto the plurality of sensor IC chips 95 by the lens array 96.
The sensor IC chips 95 output signals corresponding to the received amount of light. In the image reader X, the signals outputted from the sensor IC chips 95 are stored in a non-illustrated memory. In this way, the image reader X reads the content of the document Dc as an image.
Generally, in manufacturing the image reader X, the light guide member 94 and the reflectors 98A, 98B are assembled into an integral unit, and then, the integral unit is inserted into the case 91. To insert the integral unit into the case, the unit needs to be held properly. Thus, it is difficult to automatically and continuously perform the assembling and insertion of the integral unit, which deteriorates the manufacturing efficiency of the image reader X.
Meanwhile, there are demands for increasing the readable range of the image reader X in the primary scanning direction and making the image reader X slim. To increase the readable range and slim down the image reader X, the light guide member 94 and the reflectors 98A, 98B need to be made narrower and longer. However, such narrow and long light guide member 94 and reflectors 98A, 98B are more likely to undergo deformation such as warping or twisting. Thus, when such light guide member 94 and reflectors 98a, 98B are assembled into an integral unit, deformation may appear in the integral unit. To mount such a deformed integral unit to a predetermined position in the case 91 is difficult, so that the manufacturing efficiency is deteriorated. Further, the deformed unit causes other drawbacks such as failure of the image reading.
Patent Document 1: JP-A-2004-266313